Qiying Jiang

Control of hydroxyapatite coating by self-assembled monolayers on titanium and improvement of osteoblast adhesion.

Self-assembly technique was applied to introduce functional groups and form hydroxyl-, amine-, and carboxyl-terminal self-assembled monolayers (SAMs). The SAMs were grafted onto titanium substrates to obtain a molecularly smooth functional surface. Subsequent hydrothermal crystal growth formed homogeneous and crack-free crystalline hydroxyapatite (HA) coatings on these substrates. AFM and XPS were used to characterize the SAM surfaces, and XRD, SEM, and TEM were used to characterize the HA coatings. Results show that highly crystalline, dense, and oriented HA coatings can be formed on the OH-, NH2 -, and COOH-SAM surfaces. The SAM surface with -COOH exhibited stronger nucleating ability than that with -OH and -NH2 . The nucleation and growth processes of HA coatings were effectively controlled by varying reaction time, pH, and temperature. By using this method, highly crystalline, dense, and adherent HA coatings were obtained. In addition, in vitro cell evaluation demonstrated that HA coatings improved cell adhesion as compared with pristine titanium substrate. The proposed method is considerably effective in introducing the HA coatings on titanium surfaces for various biomedical applications and further usage in other industries.

Carboxylated chitosan/silver-hydroxyapatite hybrid microspheres with improved antibacterial activity and cytocompatibility

The implant-associated infection remains a serious problem in clinic. A better compromise between the anti-infection property and biocompatibility of bone filling materials is still required. In this work, carboxylated chitosan/silver-hydroxyapatite (CMCS/Ag-HA) hybrid microspheres were fabricated via a facile gas diffusion method. CMCS and Ag ion were evenly distributed into hybrid microspheres. CMCS regulated the morphological characteristics of the as-synthesized hybrid microspheres. As the content of CMCS increased, the size of the sample increased and dispersion exacerbated. In addition, antimicrobial studies demonstrated that CMCS/Ag-HA hybrid microspheres exhibited an excellent antimicrobial activity against Staphylococcus aureus because of the synergistic effect of Ag+ and CMCS. In vitro cell tests indicated that the as-prepared CMCS/Ag-HA hybrid microspheres promoted the proliferation and adhesion of MG63 cells. CMCS/Ag-HA hybrid microspheres showed excellent bactericidal property and biocompatibility; thus, they could be used in biomedical applications, such as infection-resistant bone replacement materials.

An effective route to the synthesis of carbonated apatite crystals with controllable morphologies and their growth mechanism

Carbonated hydroxyapatite (CHAp) powders with controllable morphologies and sizes were successfully synthesized via hydrothermal treatment by using hexamethylenetetramine (HMT) as a hydroxide anion-generating agent in a phosphate-surplus precursor solution. The products were characterized by X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and selected-area electron diffraction. The results revealed that the morphologies (such as microrods, sheet-like-assembled flowers, shaft wheel-like structures, bur-like spheres, dumbbell-shaped structures, and microspheres) of the products could be well tailored by regulating the reaction acidity and time. A possible growth mechanism accompanied by the effects of HMT on crystal nucleation and growth was preliminarily proposed for the formation of the controllable structures. This work indicated that the use of HMT as a hydroxide anion-adjusting agent is an effective strategy to finely control the morphology of CHAp crystals.

Edta-linked 5p–4f trinuclear heterometallic complex: syntheses, X-ray structure and luminescent properties

A new heterometallic antimony–samarium complex, [Sb2(edta)2Sm(H2O)4]NO3 · 3.55H2O (edta = ethylenediaminetetraacetate) (1), has been synthesized and characterized by elemental analyses (EA), Fourier transform infrared spectroscopy, thermogravimetry-differential scanning calorimetry, and X-ray crystallography. The X-ray crystal structure analysis reveals that in 1 the bridging carboxylate-O,O′ of edta4− connects samarium(III) and antimony(III) to form 2-D sheets. The 2-D sheets are further linked by bridging carboxylates from adjacent layers, resulting in 3-D coordination polymers. Complex 1 exhibits fluorescence in the solid state at room temperature.